а) $$6x - 6 = 3(10 - x)$$ $$6x - 6 = 30 - 3x$$ $$6x + 3x = 30 + 6$$ $$9x = 36$$ $$x = \frac{36}{9}$$ $$x = 4$$
Ответ: 4
б) $$3(x-1) - 2(x+5) = 8$$ $$3x - 3 - 2x - 10 = 8$$ $$x - 13 = 8$$ $$x = 8 + 13$$ $$x = 21$$
Ответ: 21